In 1994, the United Nations General Assembly proclaimed 16 September the International Day for the Preservation of the Ozone Layer, commemorating the date of the signing, in 1987, of the Montreal Protocol on Substances that Deplete the Ozone Layer (resolution 49/114).

The principal aim of the Montreal Protocol is to protect the ozone layer by taking measures to control total global production and consumption of substances that deplete it, with the ultimate objective of their elimination on the basis of developments in scientific knowledge and technological information. It is structured around several groups of ozone-depleting substances. The groups of chemicals are classified according to the chemical family and are listed in annexes to the Montreal Protocol text. The Protocol requires the control of nearly 100 chemicals, in several categories. For each group or annex of chemicals, the Treaty sets out a timetable for the phase-out of production and consumption of those substances, with the aim of eventually eliminating them completely.

Theme of 2026 is “Global action for a cooler planet”: celebrates the Montreal Protocol and the transformative impact of its Kigali Amendment ten years after adoption. The Montreal Protocol has demonstrated that science-based policy, universal participation, strong compliance, dedicated financing, and effective partnerships can deliver real and measurable results. Through these elements, the treaty has not only protected the ozone layer but also enabled countries and industries to transition to safer, more sustainable alternatives while supporting economic development.